The present invention relates to a condensing gas water heater, in particular to a forward combustion type condensing gas water heater.
Typically, known condensing gas water heaters carry out two heat exchanges during a heat exchange process. After hot flue gas is subjected to the first heat exchange, the temperature of the flue gas drops, and after the flue gas is subjected to the second heat exchange, the temperature further drops, below the dew point, and the vapor in the flue gas condenses into liquid water, thus releasing vaporization heat.
Known condensing gas water heaters typically employ one of two types of combustion, inverted combustion or forward combustion. In the inverted combustion type condensing gas water heater, the condenser is located below the burner, and in use, the condensation water can not (even in a failure condition) flow to the burner, the heat exchanger, the combustion chamber, the ignition pin, or other associated components. In the forward combustion type condensing gas water heater, the condenser is located above the burner, and normally a water gathering device is provided. In normal use, condensation water will not drop to the burner, the heat exchanger, the combustion chamber, the ignition pin, or other associated components. However, after use for a certain period of time, condensation water may not drop smoothly due to the resistance of upward rising flue gas, and moreover the flue gas may not be exhausted smoothly. If a leakage occurs, the condensation water may flow to the burner, the heat exchanger, the combustion chamber, the ignition pin, or other associated components resulting in corrosion of these parts. Therefore, the life of the water heater may be shortened, while the insulating property of the ignition pin may be reduced, so that ignition failure and even deflagration may occur.